﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace Xww.IO {
    public static class FileEncodingType {
        public static System.Text.Encoding GetType(this string FILE_NAME) {
            FileStream fs = new FileStream(FILE_NAME, FileMode.Open, FileAccess.Read);
            System.Text.Encoding r = GetType(fs);
            fs.Close();
            return r;
        }
        public static System.Text.Encoding GetType(FileStream fs) {
            /*byte[] Unicode=new byte[]{0xFF,0xFE};  
            byte[] UnicodeBIG=new byte[]{0xFE,0xFF};  
            byte[] UTF8=new byte[]{0xEF,0xBB,0xBF};*/

            BinaryReader r = new BinaryReader(fs, System.Text.Encoding.Default);
            byte[] ss = r.ReadBytes(3);
            r.Close();
            //编码类型 Coding=编码类型.ASCII;   
            if (ss[0] >= 0xEF) {
                if (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF) {
                    return System.Text.Encoding.UTF8;
                }
                else if (ss[0] == 0xFE && ss[1] == 0xFF) {
                    return System.Text.Encoding.BigEndianUnicode;
                }
                else if (ss[0] == 0xFF && ss[1] == 0xFE) {
                    return System.Text.Encoding.Unicode;
                }
                else {
                    return System.Text.Encoding.Default;
                }
            }
            else {
                return System.Text.Encoding.Default;
            }
        }
    }
}
